HA Software & Database Integrity

We are looking at using high availability software that copies data & log files from one server to another at the disk level.

Now in theory, the HA software copies a "perfect" copy of each data & log file to the destination server. Then if the main server fails, the application is pointed across to the other server data & log files.

Has anyone else used HA software like this and what issues might there be?

The main issue I can think of is how the HA software manages a smooth halt to database processing ( issuing a pause in any transaction processing ) then switching and resuming a transaction.

Another thing that bothers me is that at every stage , the copy of the data & log files will never be EXACTLY the same as the originals, and if so, how do we guarantee that the data file & log fiels wont be out of synchronisation with each other?

If you're looking for the high availability then deploy SQL Cluster before considering to use third party tools.

The Log shipping only provides the warm standby and manual intervention is required to switch over the database accessibility. Check this website about log shipping and books online for further information.